A student begins to balance the net ionic equation and recognizes that a coefficient…

CHEMISTRY · Subjective · AP · Chemistry · Chemical Reactions · Chemical Reactions

Problem

A student begins to balance the net ionic equation

Sr^{2+} + PO_{4}^{3-} \rightarrow Sr_{3}(PO_{4})_{2}(s)

and recognizes that a coefficient of 3 is needed in front of

Sr^{2+}

. In one sentence, explain why this coefficient is required.